Maintaining daily rhythm is important for mental health, study suggests

They found that people who were less active in the daytime and more active at night were more likely to have depression and bipolar disorder, less likely to describe themselves as happy, and more likely to say they were often lonely. "I don't think it's unreasonable to say this is another piece of evidence that might suggest we should all be more mindful of our natural rhythms of activity and rest", Professor Smith explained.

Our internal body clocks, or circadian rhythms, determine almost every biological process in our bodies, including sleeping, eating, and our blood pressure. With the brain's internal time-keeping system, it anticipates environmental changes and adapts to the appropriate time of day. "Previous studies have identified associations between disrupted circadian rhythms and poor mental health, but these were on relatively small samples". "This is important globally because more and more people are living in urban environments that are known to increase risk of circadian disruption and, by extension, adverse mental health outcomes".

For the new study, an worldwide team led by University of Glasgow psychologist Laura Lyall analysed data - taken from the UK Biobank, one of the most complete long-term health surveys ever done - on 91,105 people aged 37 to 73. These subjects were also more likely to have reduced feelings of well-being and lower cognitive functioning, which was measured by a computer-generated test for reaction times.

However, the new study is the first to use objective measurements of daily activity and is among the largest of its kind, according to Aiden Doherty, senior research fellow at the University of Oxford, who was not involved in the research. This limitation is compounded by the time difference between the recording of demographic and lifestyle data (2006-10), accelerometry data (2013-14) and information from the mental health questionnaire (2016-17). They occur in plants, animals and throughout biology, and are fundamental for maintaining health in humans, particularly mental health and wellbeing.

They used wearable fitness-tracking devices to assess the physical activity of 90,000 people in the United Kingdom, and then compared the results with associated questionnaires looking at mood and mental health outcomes.

"It might be that the UK Biobank provides the impetus for a resource of a similar scale in adolescents and younger adults to help transform our understanding of the causes and consequences, prevention and treatment of mental health disorders". "That's not a big surprise", said Dr. Daniel Smith, professor of psychiatry at the University of Glasgow and a leading author on the study.

[1] Quotes direct from authors and can not be found in text of Article. People with less of a distinction between active and resting periods scored a lower amplitude, either because they were not active enough during while they were awake or too active in the hours intended for sleep. This was in comparison to participants who followed a normal cycle of being active during the day and switching to rest at night.